I am trying to emulate an optics table.  I need narrow cylindrical beams of
light, that reflect off mirrors and refract through lenses and interact with
the media in a 'fog box'. I am /almost/ there.

I've tried everything I can think of to get a laser beam effect that has
photon interaction with media. The following works, but /only/ with a
spotlight.  When I use a cylindrical light, the refracted (or reflected)
photons stop interacting with the media.  Any ideas?

BTW, the parallel modifier causes /all/ the media to light up. Sigh.

My understanding is shrinking along with any ego I might have previously
possessed. My wife is going home to mama.  My mortgage is in arrears. My
hair is gone. I giggle a lot, then burst into uncontrolled tears. I am
hopelessly addicted.
--------------------------------------
#version 3.5;

#include "colors.inc"
#include "textures.inc"

global_settings {
  assumed_gamma 1
  max_trace_level 25

  photons {
    spacing 0.03
    media 100
    autostop 0
    jitter 0
  }
}

light_source {
    <0, 30, 0> *2
    color White * 1
}

camera {
    orthographic
    location <0,17,0>
    look_at <0,0,0>
}

box { // fog box
    <-9,-2,-9>,<9,2,9>
    pigment { White filter 1 }
    hollow on
    photons {pass_through}
    interior{
        media {
        scattering { 1, rgb 0.03}
        intervals 1
        samples 5
        method 3
        }

    }
}

    light_source {  //spotlight
        0*x
        color Green * 3
        //cylinder
        spotlight
        translate <-15,.5,4>
        point_at <0,.5,4>
        radius 1
        tightness 90
        falloff 5
        photons {
            refraction on
            reflection on
        }
    }

intersection {// lens
    intersection {
        sphere {
            <0, 4.95, 0>, 5
        }
        sphere {
            <0, -4.95, 0>, 5
        }
        scale <1,1,1> * 8
    }
    cylinder {
        <0, 3, 0>,
        <0, -3, 0>,
        7.0
    }
    material {
      M_NB_Glass
    }
    photons {
        target
        refraction on
        reflection off
    }

    rotate z*90
    translate -x * 7
}

--------------------------------------

Alan Walkington

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Alan Walkington wrote:
> 
> I am trying to emulate an optics table.  I need narrow cylindrical beams of
> light, that reflect off mirrors and refract through lenses and interact with
> the media in a 'fog box'. I am /almost/ there.

Use a point light, put it into a slotted box. That's what I did.

-- 

------------------------------------------------------------------------
 +47 90 62 71 78          DoD#2101, DoDRT#017, NIC#015, PJ#006, OGM#007
 azo### [at] dodno, Ducati M600, Audi 100 2.3E Ubesudlet: Aldri eid en J&%#PS

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"Alan Walkington" <alan[REMOVE]@walkington.net> wrote in message
news:3e8e32d4@news.povray.org...

> I've tried everything I can think of to get a laser beam effect that has
> photon interaction with media. The following works, but /only/ with a
> spotlight.  When I use a cylindrical light, the refracted (or reflected)
> photons stop interacting with the media.  Any ideas?

This sucks. I've got a sort of usable laser effect by sticking a point light
insde the closed end of a veeery looong cylindar open at the far end.  The
results are adequate, but its /very/ difficult to manouver. (A quick aside
... How is the center of rotation computed?)
-------------------
#declare GreenLaser = union {
    difference {
        cylinder {
            <-1,0,0>
            <60,0,0>
            .3
        }
        cylinder {
            <-.9,0,0>
            <60.1,0,0>
            .2
        }
    }
    light_source {
        <0.0.0 >
        color Green *20
    }
    texture {Polished_Chrome}
}

-------------------
Alan Walkington

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Alan Walkington <alan[REMOVE]@walkington.net> wrote in message
news:3e8e8437@news.povray.org...

> (A quick aside
> ... How is the center of rotation computed?)

The center of rotation is <0,0,0>.

RG

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> Alan Walkington wrote:
>> 
>> I am trying to emulate an optics table.  I need narrow cylindrical beams of
>> light, that reflect off mirrors and refract through lenses and interact with
>> the media in a 'fog box'. I am /almost/ there.
> 
> Use a point light, put it into a slotted box. That's what I did.

I usually have a very distant spotlight with projected_through on some near 
object. That makes it *almost* parallel but then it's possible that POV 
might "miss" the projected_through object and shoot no photons into the 
scene at all... There's usually some happy medium though! :-)

-- 
light_source#macro G(E)sphere{z+E*y*5e-3.04rotate-z*E*6pigment{rgbt#end{
20*y-10#local n=162;1}#while(n)#local n=n-.3;G(n)x}}G(-n).7}}#end//GregE

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